The present invention relates to the technical fields of the Food Industry, the Medical-Pharmaceutical Industry and the Chemical Industry. The product resulting from the modification of the proteins of industrial organic wastes, known as peptones, will be of use in the following applications:
Human and animal nutrition
Clinical nutrition
Nitrogenated fermentation source in the Pharmaceutical Industry.
Soluble organic fertilisers
The generation of protein-rich industrial wastes is very high (only from sunflower, about one million tons in Spain). These wastes are not used at all, or are underused in the form of low added-value products.
This type of by-products constitute a reservoir of proteins with a great economic potential.
The main obstacle for their direct use is constituted, on one hand, by the presence of antinutritional substances (pigments, alkaloids), and on the other by the deficient physical properties of the proteins. One of these deficiencies is their insolubility, motivated essentially by the treatments through which these raw materials have been subjected in the industrial processes (high temperatures, treatments with organic solvents, etc).
The use of these peptones in the human and animal food industry, as well as in other types of industry, such as the pharmaceutical (as a nitrogen source for fermentation) or the chemical industry (organic fertilisers), requires the development of the appropriate processes:
a) For the elimination of undesirable substances; soluble sugars, fibres, alkaloids, etc.
b) For the extraction of protein leading to the recovery of the protein in the by-product and yielding a new product, completely proteinaceous, which is soluble under any condition (temperature, pH and in the presence of metal ions).
The solubility of the recovered proteinaceous product will permit its use in liquid products within the industrial fields mentioned above (clinical nutrition, enteral, parenteral and maintenance diets, fermentations, organic fertilisers, etc).
The solution to this problem will be the development of processes for the preparation of agro-industrial wastes for their conversion into ideal substrates with solubilised proteins.
The solubilisation of these proteins will be carried out enzymatically, using proteases, which will modify the proteins by the hydrolytic cleavage of their polypeptide chains, with the subsequent production of protein hydrolysates (peptones).
Research in the field of human nutrition is currently focused on obtaining products that can be used to control, through the diet, chronic diseases such as arteriosclerosis, cancer, AIDS, hepatic and renal failure, as well as on obtaining products for weight control and for the nutritional control of hospitalised patients [Fxc3xcrst, P (1989) Use of short chain peptides in clinical nutrition. J. Clin. Nutr. Gastroenterol., 205-211] and in animal nutrition the aim is obtaining specific diets for livestock animals (calf, fattened pigs and suckling animals, etc).
The use of protein hydrolysates has a number of advantages:
a) The component peptides are absorbed very effectively in the digestive tract as the original protein has already undergone a prior digestion, making absorption rapid and complete (Matthews, M. D. Protein absorption. Then and now. Gastroenterology 73, 1267-1279; 1977).
b) At a physiological level they present a better utilisation than equivalent mixtures of free amino acids, and the osmotic pressure produced is much lower than that of the corresponding amino acid mixture.
In this context the preparation of hydrolysates is useful in the production of physiologically functional foods to cover specific needs, such as those destined to patients suffering malnutrition associated to cancer, severe burns, multiple traumatism and hepatic diseases (Keith, M. E. and Jeejeebhoy K. N. Enteral nutrition in wasting disorders. Curr. Opin, Gastroenterol. 15, 159-166; 1999; Fischer J. E. Branched-chain enriched amino acid solution in patients with liver failure: An early example of nutritional pharmacology. J. Parenter-Enteral Nutri. 14, 249S-256S.; 1990), and as nutritional support in children with acute and chronic diarrhoea or allergy to dairy proteins (Buzinco L., et al Anaphylactic reaction to a cow""s milk whey protein hydrolysate in infants with cow""s milk allergy. Ann Allergy 62, 333-335, 1989).
With respect to other similar patented processes (WO98/23170 and WO92/11771), the main difference with the process of the invention is that on those patents, the enzymatic hydrolysis is carried out on soluble protein that has been obtained via a previous chemical treatment of the waste. This previous treatment generally consists in using soda at pH 10. In the present invention the solubilisation of the proteins is carried out by means of direct enzymatic extraction without prior chemical treatment. Additionally, WO98/23170 also employs a previous extraction with alcohol, to eliminate the polyphenols present in the waste. In the present invention the polyphenols are removed by successive washing steps with acidified water. Not using soda or alcohol extraction steps implies a considerable saving in terms of equipment, installations and solvents. Additionally, water is discharged into the environment, instead of more aggressive solvents that require previous pretreatment which is more complex and costly.
In Parrado et al. (J. Agric. Food Chem. 1991), a similar process is described, but limited to degreased sunflower flour, employing a specific protease (Kerasa(copyright)). Additionally, in said article the process is carried out discontinuously in the laboratory, in batches, whereas in this invention the process is carried out continuously, industrially, employing any protease existing in the market and applying a wide range of industrial wastes of plant origin.